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FILM WELDING BY MICROWAVE HEATING WITH LOCALIZED ADSORBER

IP.com Disclosure Number: IPCOM000026938D
Original Publication Date: 1994-Jun-30
Included in the Prior Art Database: 2004-Apr-07
Document File: 4 page(s) / 200K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed is a process and apparatus where microwave energy is used to thermally weld two plastic film materials so that a continuous film surface, such as an endless belt, is formed. The plastic film materials are such that they can be melted by heating. The film materials are overlapped with a metal conductor located at the center of the overlapped region. The microwave energy is adsorbed by the metal conductor which is, in turn, heated to a temperature such that the surrounding plastic film material melts and combines to form a continuous plastic region. The molten plastic solidifies with cooling, after the removal of the microwave energy, to form an excellent mechanical bond between the two films with the metal conductor embedded at or near the center of the weld region. The advantages of this method for welding two plastic films are that the heat is applied directly at the interface of the two films and thus efficient heating occurs, and the surfaces of the film adjacent to the bond are not thermally distorted by the welding process. The bonding process for end sections of thin, flexible, multi-layered film, overlapping first and second ends of the film to be bonded; placing a metal conductor between the overlapping first and second film ends; clamping the metal conductor between the overlapping first and second film ends; and applying microwave energy from a microwave energy source to the overlapping first and second film ends, with the metal conductor disposed therebetween, to evenly heat the metal conductor causing the overlapping first and second film ends to melt and mix in the vicinity of the metal conductor, to form a mechanical bond after cooling and upon removal of the microwave energy.

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Page 1 of 4

XEROX DISCLOSURE JOURNAL

FILM WELDING BY MICROWAVE HEATING WITH LOCALIZED U.S. C1.430/059 ADSORBER Int. C1. G03g 05/06 Donald S. Sypula

Proposed Classification

I I

18

I

20 18

\

FIG. I

20 18

FIG. 2

XEROX DISCLOSURE JOURNAL - Vol. 19, No. 3 May/June 1994 259

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Page 2 of 4

FILM WELDING BY MICROWAVE HEATING WITH LOCALIZED ADSORBER (Cont'd)

Disclosed is a process and apparatus where microwave energy is used to thermally weld two plastic film materials so that a continuous film surface, such as an endless belt, is formed. The plastic film materials are such that they can be melted by heating. The film materials are overlapped with a metal conductor located at the center of the overlapped region. The microwave energy is adsorbed by the metal conductor which is, in turn, heated to a temperature such that the surrounding plastic film material melts and combines to form a continuous plastic region. The molten plastic solidifies with cooling, after the removal of the microwave energy, to form an excellent mechanical bond between the two films with the metal conductor embedded at or near the center of the weld region. The advantages of this method for welding two plastic films are that the heat is applied directly at the interface of the two films and thus efficient heating occurs, and the surfaces of the film adjacent to the bond are not thermally distorted by the welding process. The bonding process for end sections of thin, flexible, multi-layered film, overlapping first and second ends of the film to be bonded; placing a metal conductor between the overlapping first and second film ends; clamping the metal conductor between the overlapping first and second film ends; and applying microwave energy from a microwave energy source to the overlapping first and second film ends, with the metal conductor disposed therebetween, to evenly heat the metal conductor causing the overlapping first and second film ends to melt and mix in the vicinity of the metal conductor, to form a mechanical bond after cooling and upon removal of the microwave energy.

The method is applicable to polymer welding generally. For a general understanding of the method, reference is made to the Figures. Two ends 12, 14 of a multi-layer polymeric material, to be joined, are shown overlapped with a metal conductor 20 inserted therebetween. Figure 1 shows the two ends 12, 14 before microwave heating and Figure 2 shows the result after microwave heating. The top layer 16 of the composite film is, for example, TEDLAR@ which is bonded onto polycarbonate with carbon film 18. The metal conductor 20, which can be in the form of a fine wire, multiple parallel fine wires, powder or wire grid (as shown in Figure 1 as a fine wire, the preferred conductor for most welding), is positioned between the overlapped film end sections in the region where the seam is to be formed. The amount of overlap of the film end sections can be on the...